1. Field of the Invention
The present invention relates to an adsorbent for oily materials mainly comprising unrefined lints (hereinafter, referred to as crude lints) or unrefined linters (hereinafter, referred to as crude linters) having high water repellency and a high oil adsorptive function for collecting or removing oily materials floating on the surface of the water or oily materials emulsified or dispersed in water as well as oily solvents insoluble in water.
The invention further relates to a process of treating oil-containing waste water using the above-described adsorbent.
2. Description of the Prior Art
When oils, in particular, mineral oils are present in rivers or public water reservoirs, they contaminate the water and damage greatly sources for aquatic or marine products in river basins and the coasts near rivers.
Thus, to prevent the occurence of such damage by water pollution, regulations on waste water have become quite strict and countermeasures have been provided, when by any chance oil-containing waste water flows into a river, that oily materials are collected or recovered as quickly as possible to prevent these oily materials from spreading over the river.
As countermeasures for preventing the spreading of oily-materials which have flowed into a river, various methods have been proposed and one of the most effective methods is a method in which an adsorbent for oily materials is effectively utilized.
Hitherto, as the adsorbents for oils floating on the surface of the water, regenerated celluloses comprising mixtures of various pulps and rayon; fibers comprising a synthetic polymer such as polypropylene, polystyrene, polyurethane, etc.; or sponges are mainly used and as adsorbents for fine oil droplets dispersed in water, synthetic fibers comprising a hydrocarbon polymer such as polypropylene, etc., are mainly used.
However, regenerated celluloses have the disadvantages that an adsorbent comprising such regenerated celluloses are expensive since they must be treated to render them water repellent due to the high hydrophilic property of these materials and these regenerated celluloses do not always have good oil adsorption properties. Also, oil adsorbents comprising synthetic fibers have various difficulties in practical use since they have a low adsorption retention for low viscosity oils, they generate a large amount of heat on incineration, which causes difficulties, they do not retain their structural form depending on the solvents contained in the waste water to be treated, and also the cost of the synthetic fibers is high.
As mentioned above, oil adsorbers reserved for countermeasures for leakage of oily materials at present have various disadvantages from the standpoint of their properties as well as cost and adsorbents which sufficiently overcome these difficulties have not yet been developed.